Field of the Invention
The present invention relates to an organic light emitting display device and a method of manufacturing the same.
Discussion of the Related Art
As a type of new flat panel display device, organic light emitting display devices are self-illumination display devices, and have a better viewing angle and contrast ratio than liquid crystal display (LCD) devices. Also, since the organic light emitting display devices do not need a separate backlight, it is possible to lighten and thin the organic light emitting display devices, and the organic light emitting display devices have excellent power consumption compared to LCD devices and the other flat panel display devices. Furthermore, the organic light emitting display devices are driven with a low direct current (DC) voltage, have a fast response time, and are low in manufacturing cost.
In organic light emitting display devices, an electron and a hole are respectively injected from a cathode and an anode into a light-emitting material layer, and, when an exciton in which the injected electron and hole are combined is shifted from an excited state to a base state, light is emitted. In this case, the types of organic light emitting display devices are categorized into a top emission type, a bottom emission type, and a dual emission type according to an emission direction of light, and categorized into a passive matrix type and an active matrix type according to a driving type.
Specifically, the organic light emitting display devices include a first electrode (anode), a hole transporting layer, a light-emitting material layer including a red organic emission pattern, a green organic emission pattern, or a blue organic emission pattern, an electron transporting layer, and a second electrode (cathode), which are formed in each of a red pixel area (P1), a green pixel area (P2), and a blue pixel area (P3).
In the organic light emitting display devices having the configuration, when a voltage is applied to the first and second electrodes, a hole moves to the light-emitting material layer through the hole transporting layer, an electron moves to the light-emitting material layer through the electron transporting layer, and the hole and the electron are combined in the light-emitting material layer, thereby emitting light. In this case, the pixel areas have different wavelengths of light, and thus, an optical distance should be adjusted for adjusting a desired color purity and intensity. Generally, the hole transporting layers in the respective pixel areas are formed to have different thicknesses, and adjusting the thickness of the hole transporting layers affects a mobility characteristic of a hole.
However, when the mobility characteristic of a hole is degraded, an electric charge imbalance of the light-emitting material layer occurs, and consequently affects a light output efficiency and service life characteristic of a device.
For this reason, various methods of manufacturing an organic light emitting display device are being required for enhancing a light output efficiency and a service life in consideration of the mobility characteristic of a hole.